1. Field of the Invention
The invention relates generally to a communication network system, a network switch and bandwidth control, for site-to-site communications.
2. Description of the Related Art
Each of many enterprises has a plurality of sites (e.g., a data center site, and local branch sites) which are geographically distributed over a wide area. In such an enterprise, “site-to-site communications” are established between selected ones of the sites, over a shared enterprise-network which is configured by interconnecting a plurality of LANs (Local Area Networks) located on a per-site basis, so as to span a wide geographical area.
Typical types of wide area networking include: a first type in which the sites are mutually communicated by point-to-point leased- or dedicated-line services; and a second type in which the sites are mutually communicated over a multi-point VPN (Virtual Private Network) service network, such as IP (Internet Protocol)-VPN or a Wide Area Ethernet (Registered Trademark) network.
The second type, as compared with the first type, is advantageous in implementing low-cost and high-speed site-to-site communications, resulting in the growing shift to site-to-site communications using a VPN service network.
Currently, many enterprises, aiming at centralized management of information asset, and compliance such as internal control and personal information protection, are promoting centralization to a date center, of resources such as servers or storages (hereinafter, referred to as “resource centralization”). The resource centralization reduces the burden of managing operation of systems such as servers and storages, and saves the required costs through the resulting system hardware integration.
FIGS. 1A and 1B illustrate the configuration of a conventional site-to-site communications system.
As illustrated in FIG. 1B, a plurality of private networks such as LANs are located at a plurality of sites are linked. These private networks are linked through respective routers and respective communication lines, with respective network switches 1. These network switches 1 participate in a shared network in the form of a carrier network 2 (i.e., a network administered by a telecommunication company) represented by a VPN service network. In an example, these sites include a data center site at which a data center is located, and a plurality of local branch sites. As illustrated in FIG. 1A, the local branch sites are geographically distributed, and utilize shared resources such as servers or storages located at the data center.
Such conventional networking is disclosed in, for example, Japanese Patent Application Publication Nos. 2002-232461 and 2004-529546, the contents of which are incorporated herein by reference in their entirety.